On Tue, Mar 14, 2017 at 05:14:12PM -0400, valdis.kletnieks at vt.edu wrote:

On Tue, 14 Mar 2017 21:59:20 +0100, Bj?rn Mork said:

quoted

And another one:

 5.) vendor independent class drivers


IMHO perfect for the independent developer since there will be
documentation available.  The USB class specs are freely available for
example.

Hmm... /sys/class has a bunch of stuff already.

/sys/class has nothing to do with a USB class specification :)

How many class drivers
are missing from there? And more importantly, class drivers for a hardware
class that's actually available (i.e. neither extinct or not shipping yet)?

A USB "class" is a set of devices that follow a published specification.
Like a USB HID device (keyboard/mouse/etc.)  These are all published on
the usb.org website.  I think there still are a few class specs that are
not yet implemented on Linux, usually because no one actually made any
devices for them, or not enough that anyone really cares.

A /sys/class/ entry is a kernel subsystem that describes a set of
devices that interact with userspace in a defined way.  Like an "input"
class.  That is how userspace interacts with _all_ keyboards, be they
USB or PS/2 or i2c or whatever.

Hope this helps,

greg k-h